i dont think a cz or 1911 would get an A/D when dropped with a round in chamber and hammer down. because the hammer needs to travel in order to strike the firing pin. but when the hammer is rested on the slide, impact energy from the drop would not send the firing pin forward .for sig's , it's a little different. there's a gap between the hammer and the firing pin. if the hammer was hit hard enough , the gun might go off but i dont think dropping from waist height is enough to get an AD. unless the gun was thrown down from 3rd floor by a major league pitcher and landed right on the hammer. hammer back and safety on is probably the most dangerous wany to carry a 1911. if it was dropped hard enough ,even tho the manual safety blocks the sear , the hammer or the sear could break and release the hammer forward. if the sear broke, the half #### safety catch might not work to stop the hammer (given that the gun was drop hard enough on the hammer to break the sear in the first place) .
if i was allowed to carry a gun, i wouldn't carry my 1911 hot with safety on. it's takes zero effort to disengage the extended safety , my shirt catching it wouldve done the trick. the trigger is way too light to boot . i would only carry it with no rounds in the chamber. it takes no time to rack the slide when you need it.
as for choosing between decock or MS. i'd probably take decock . the chance of using either feature in canada is slim . when at the range, the gun is either rest on the bench with an open slide. or in your hand ready to shoot. for competition , you could use the decocker before holstering the gun at "make ready" stage. but i trust my index and thumb to lower the hammer more than a mechanical piece.